我想在我的 Fortran 代码中为派生类型实现用户定义的 I/O 过程。但是，write这些过程中的语句不能在两个连续write语句之间产生新行。派生类型和过程定义如下。
模块：
module station_module
implicit none
character(8), parameter :: FmtFloat = '(5E15.7)'
type :: station
integer, private :: ns = 0
real, public, allocatable :: xloc(:), yloc(:), zloc(:)
contains
procedure, public :: import_station
procedure, public :: export_station
procedure, private :: read_station
generic, public :: read (formatted) => read_station
procedure, private :: write_station
generic, public :: write (formatted) => write_station
final :: destruct_station
end type station
interface station
module procedure new_station
end interface station
contains
function new_station(n) result(t)
implicit none
integer, intent(in) :: n
type(station) :: t
if (n > 0) then
allocate (t%zloc(n))
allocate (t%yloc(n))
allocate (t%xloc(n))
t%ns = n
end if
end function new_station
subroutine read_station(dtv, unit, iotype, vlist, iostat, iomsg)
implicit none
class(station), intent(inout) :: dtv
integer, intent(in) :: unit
character(*), intent(in) :: iotype
integer, intent(in) :: vlist(:)
integer, intent(out) :: iostat
character(*), intent(inout) :: iomsg
call dtv%import_station(unit)
iostat = 0
end subroutine read_station
subroutine import_station(this, unit)
implicit none
class(station), intent(inout) :: this
integer, intent(in) :: unit
character(256) :: header, footer
integer ns
read (unit, '(A)') header !> Header
read (unit, *) ns
if (ns > 0) then
if (allocated(this%zloc)) then
deallocate (this%zloc)
end if
allocate (this%zloc(ns))
read (unit, *) this%zloc
if (allocated(this%yloc)) then
deallocate (this%yloc)
end if
allocate (this%yloc(ns))
read (unit, *) this%yloc
if (allocated(this%xloc)) then
deallocate (this%xloc)
end if
allocate (this%xloc(ns))
read (unit, *) this%xloc
this%ns = ns
end if
read (unit, '(A)') footer !> Footer
end subroutine import_station
subroutine export_station(this, unit)
implicit none
class(station), intent(in) :: this
integer, intent(in) :: unit
write (unit, '(A)') ">STATION INFO"
write (unit, '(I6)') this%ns
write (unit, *) "Z:"
write (unit, FmtFloat) this%zloc
write (unit, *) "Y:"
write (unit, FmtFloat) this%yloc
write (unit, *) "X:"
write (unit, FmtFloat) this%xloc
write (unit, '(A)') ">END STATION"
end subroutine export_station
subroutine write_station(dtv, unit, iotype, vlist, iostat, iomsg)
implicit none
class(station), intent(in) :: dtv
integer, intent(in) :: unit
character(*), intent(in) :: iotype
integer, intent(in) :: vlist(:)
integer, intent(out) :: iostat
character(*), intent(inout) :: iomsg
call dtv%export_station(unit)
iostat = 0
end subroutine write_station
subroutine destruct_station(this)
implicit none
type(station), intent(inout) :: this
if (allocated(this%xloc)) then
deallocate (this%xloc)
end if
if (allocated(this%yloc)) then
deallocate (this%yloc)
end if
if (allocated(this%zloc)) then
deallocate (this%zloc)
end if
this%ns = 0
end subroutine destruct_station
end module station_module
我们可以看到，用户定义的格式化 write语句只是调用了一个名为 的常规子例程export_station，我希望这两种方式的结果相同。
这是我的测试程序：
program Test
use station_module
implicit none
type(station) :: pt, pt1, pt2
pt = station(4)
write(*, *) pt
call pt%export_station(6)
end program Test
输出：
>STATION INFO 4Z: 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
Y: 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00X: 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00>END STATION
>STATION INFO
4
Z:
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
Y:
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
X:
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
>END STATION
常规子程序export_station产生我所期望的。两个write语句之间会产生新行，而write派生类型的语句不会。